Forward-looking imaging systems, methods, apparatuses, media, and program products suitable for single-channel arrays

Abstract

The application belongs to the technical field of radar imaging, and discloses a forward-looking imaging system suitable for a single-channel array, a method, equipment, a medium and a program product, the system comprising a phased array transmitting antenna of multiple array elements, a single-channel receiving antenna and a processor; the method is based on the system, and steps include: constructing a coding matrix, making each array element switch an array codebook according to a modulation rate, constructing a single-channel echo model, constructing a space-time radiation field matrix through a coding modulation process and generating an imaging matching mask matrix, after sampling a single-channel echo, realizing recovery of a target scene backscattering coefficient through correlation matching with the matching mask, and completing radar forward-looking imaging; the equipment and the medium are used for realizing the method; the program product contains a computer program for realizing the method; the application can realize single fast time imaging of a three-dimensional space full scene under single-channel receiving conditions, and improve imaging refresh rate and reconstruction efficiency of a dynamic scene.

Description

Technical Field

[0001] This invention belongs to the field of radar imaging technology, specifically relating to a forward-looking imaging system and its method, device, medium and program products suitable for single-channel arrays, which can be applied to the field of forward-looking imaging radar under platform conditions such as vehicle-mounted, airborne, and missile-borne. Background Technology

[0002] Radar imaging technology is a target perception method capable of operating all-weather, all-day, and at long distances, with a wide range of applications. Compared to synthetic aperture radar (SAR), which is based on the range-Doppler principle and whose range resolution depends on the transmitted signal bandwidth and azimuth resolution depends on the radar antenna aperture, and multi-antenna array radar that uses multi-channel data to achieve forward-looking imaging, single-channel array forward-looking imaging radar has advantages such as low system complexity and fast imaging, making it highly valuable for applications.

[0003] Currently, there are few reports on single-channel imaging radar, and the existing technologies mainly include the following two: First, Li Yunbo's team proposed an aperture-coded imaging method based on information metamaterials in their paper "Transmission-type 2-bit programmable metasurface for single-sensor and single-frequency microwave imaging" (Li YB, Li LL, Xu BB, et al. Transmission-Type 2-Bit Programmable Metasurface for Single-Sensor and Single-Frequency Microwave Imaging[J]. Scientific Reports, 2016, 6:23731.DOI:10.1038 / srep23731.). They used a transmissive programmable metamaterial and achieved single-frequency aperture-coded imaging through phase modulation.

[0004] Secondly, Li Lianlin's team proposed a deep learning-driven information metamaterial inverse scattering imaging method in their paper "Machine-learning reprogrammable metasurfaceimager" (Li L, Ruan H, Liu C, et al.Machine-learning reprogrammable metasurface imager[J].NatureCommunications, 2019, 10(1).DOI:10.1038 / s41467-019-09103-2.), which uses optical sensing as a label to achieve information reconstruction of dynamic scenes.

[0005] Existing technology one employs a periodic encoding method, relying on multiple fast-time echo data for a single imaging session, making it difficult to handle highly dynamic scenes in terms of encoding strategy. Existing technology two relies on deep learning, which can improve reconstruction efficiency under specific training, but its performance is significantly dependent on the training samples and scene statistical characteristics. It is prone to insufficient generalization when the target morphology, scattering mechanism, or working mechanism changes, and it also cannot achieve high frame rate imaging. Both of these existing technologies only study forward-looking imaging problems based on information metamaterials, and are limited by: employing a large number of codes, resulting in long echo acquisition times and significantly increasing the single imaging time; and limited actual hardware performance, with encoding rates insufficient to support a large number of codes within a single fast time interval. In summary, existing solutions cannot achieve imaging in highly dynamic scenes or 3D imaging. Summary of the Invention

[0006] To overcome the shortcomings of the prior art, the present invention aims to provide a forward-looking imaging system, method, device, medium, and program product suitable for single-channel arrays. It designs the encoding matrix based on orthogonal matrices to achieve the shortest total encoding time without sacrificing imaging resolution. It constructs an imaging matching mask matrix based on radiation signals and recovers the back reflection coefficient of the target scene from the echo signal through the imaging matching mask matrix to complete radar forward-looking imaging. It has the characteristics of three-dimensional high frame rate imaging of space targets in high dynamic scenes.

[0007] To achieve the above objectives, the technical solution adopted by the present invention is as follows: A forward-looking imaging system suitable for a single-channel array, comprising A phased array transmitting antenna, a single-channel receiving antenna, and a processor for each array element; The phased array transmit antenna is used to receive radio frequency signals fed from the radio frequency baseband. and according to the encoding matrix According to modulation rate Switch codebook, change radio frequency signal Perform array-coded modulation into a radiated signal radiated signal It arrives at the target surface after being transported through space; A single-channel receiving antenna is used to receive the echo signal backscattered from the target surface. ; The processor is used to construct the encoding matrix of the phased array transmit antenna. and the radiated signal modulated by the phased array transmitting antenna. Construct an imaging matching mask matrix Based on imaging matching mask matrix The echo signal received from the single-channel receiving antenna Recovering the back reflection coefficient of the target scene This completes the forward-looking imaging.

[0008] A forward-looking imaging method based on a forward-looking imaging system suitable for a single-channel array includes the following steps: Step 1: Construct the encoding matrix of the phased array transmit antenna based on the orthogonal matrix. ; Step 2, each element of the phased array transmitting antenna is encoded according to the coding matrix. According to modulation rate Switch codebook, change radio frequency signal Perform array-coded modulation into a radiated signal radiated signal After being transmitted through space to the target surface, the signal is backscattered by the target surface and received by the single-channel receiving antenna, resulting in a single-channel echo signal. ; Step 3, based on radiation signal Construct an imaging matching mask matrix ; Step 4, based on the imaging matching mask matrix From the echo signal Recovering the back reflection coefficient of the target scene This completes the forward-looking imaging.

[0009] Step 1 specifically involves: Constructing complex orthogonal matrices ,satisfy ,in, Represents the field of complex numbers. Indicates the number of array elements. This indicates the conjugate transpose. Represents the identity matrix; definition For complex orthogonal matrices The set of elements that appear in, and ,in, The number of quantization bits for phase modulation of array elements; Introducing one-to-one mapping ; Define the encoding matrix Encoding matrix The elements are .

[0010] Step 2 specifically involves: With the center of the phased array surface as the origin O, a Cartesian coordinate system is constructed. The X and Y axes of the Cartesian coordinate system are parallel to the array surface plane, and the Z axis is perpendicular to the array surface plane and points to the normal direction of the array. The array surface is the geometric plane that defines the phased array for receiving or transmitting signals; The radiation signal For a moment Downward target angle Radiated signal, azimuth Defined as the angle relative to the X-axis, elevation angle Defined as the angle relative to the Z-axis; in, express The composite complex gain of the radiated signals of each sub-encoded element in space is expressed as: in, Indicates the number of array elements. Indicates the first Far-field radiation pattern of each array element Indicates the first The spatial orientation vector of each array element is represented as: in, This indicates the element spacing of the phased array transmitting antenna along the X-axis. This represents the element spacing of the phased array transmitting antenna along the Y-axis. Indicates the first The element number of each array element in the X-axis direction, Indicates the first The array elements are numbered in the Y-axis direction, and the array element numbers start from 1; Indicates the first The array element in the first The phase modulation coefficients of the secondary encoding, where... The number of quantization bits for phase modulation of array elements; Represents a rectangular window function, symbol period This indicates the time taken for one encoding operation. Total encoding time, radio frequency signal For a total coding time Within a certain time period, the radio frequency signal fed into the phased array transmitting antenna ; Radiated signals Acting on distance After setting the goals, from the perspective of each goal... The reflected signals are synthesized into an echo signal within a single channel. : in, At the speed of light, The target quantity.

[0011] Step 3 specifically involves: Constructing the spacetime radiation field matrix The space is discretized into a grid, where... Represents the field of complex numbers. For all spatial angles to be imaged quantity, For time Number of internal sampling points It is expressed as follows: Constructing an imaging matching mask matrix , ,in, This indicates finding the conjugate of the elements. The Fourier transform basis matrix has the following elements: .

[0012] Step 4 specifically involves: The echo from the single-channel receiving antenna is obtained by using an ADC sampling method. , For time Number of internal sampling points; Construct the back reflection coefficient of the target scene : in, Represents the field of complex numbers. For all spatial angles to be imaged quantity, For time Number of internal sampling points The basis matrix for the inverse Fourier transform is... This represents the Hadamard product of the array.

[0013] A forward-looking imaging device suitable for a single-channel array, comprising: Memory: Used to store computer programs that implement forward-looking imaging methods suitable for single-channel arrays; Processor: Used to implement a forward-looking imaging method suitable for a single-channel array when executing the computer program.

[0014] A computer-readable storage medium storing a computer program that, when executed by a processor, implements the steps of a forward-looking imaging method suitable for a single-channel array.

[0015] A computer program product includes a computer program that, when executed by a processor, implements a forward-looking imaging method suitable for a single-channel array.

[0016] Compared with the prior art, the beneficial effects of the present invention are as follows: 1. The maximum number of encoding times for the radiation signals of each array element in this invention. Equal to the number of array elements Therefore, it satisfies the requirement of obtaining an equivalent number of independent spatial observation degrees of freedom consistent with the number of array elements, at the modulation rate. Given a specific timeframe, this invention reduces the total encoding time while maintaining the same imaging resolution. To achieve the minimum, thus having the shortest total encoding time.

[0017] 2. This invention employs array elements according to modulation rate. Switching codebooks for radio frequency signals By performing array-coded modulation, coded observations that can be used for single-channel imaging are formed, thus providing a coding basis for high refresh rate imaging and achieving the effect of a large number of codes in a fast time.

[0018] 3. This invention is based on an encoding matrix. Constructing an imaging matching mask matrix From a single-channel echo signal Recovering the back reflection coefficient of the target scene This enables precise separation and reconstruction of multi-dimensional dynamic target information from single-channel echoes, improving matching and reconstruction effects under single-channel conditions, thereby achieving high-frame-rate 3D imaging and possessing the ability to image the entire 3D space scene in a fast time.

[0019] In summary, this invention enables a large amount of encoding within a short total encoding time under single-channel receiving conditions, achieving single-time fast imaging of the entire three-dimensional scene, and improving the imaging refresh rate and reconstruction efficiency of dynamic scenes. Attached Figure Description

[0020] Figure 1 This is an architecture diagram of the system described in this invention.

[0021] Figure 2 This is a flowchart of the method described in this invention.

[0022] Figure 3 This is a schematic diagram of the simulated target location in this invention.

[0023] Figure 4 This is an image showing the imaging results of the present invention. Detailed Implementation

[0024] The present invention will now be described in detail with reference to the accompanying drawings.

[0025] like Figure 1 As shown, a forward-looking imaging system suitable for a single-channel array includes... The phased array transmitting antenna, single-channel receiving antenna, and processor are provided for each array element. In this embodiment, the processor is a CPU. In other embodiments, the processor may also be an FPGA or a GPU. The phased array transmit antenna is used to receive radio frequency signals fed from the radio frequency baseband. and according to the encoding matrix According to modulation rate Switch codebook to switch radio frequency signals Perform array-coded modulation into a radiated signal radiated signal It arrives at the target surface after being transported through space; A single-channel receiving antenna is used to receive the echo signal backscattered from the target surface. ; The processor is used to construct the encoding matrix of the phased array transmit antenna. and the radiated signal modulated by the phased array transmitting antenna. Construct an imaging matching mask matrix Based on imaging matching mask matrix The echo signal received from the single-channel receiving antenna Recovering the back reflection coefficient of the target scene This completes the forward-looking imaging.

[0026] like Figure 2 As shown, a forward-looking imaging method suitable for a single-channel array includes the following steps: Step 1: Construct the encoding matrix of the phased array transmit antenna based on the orthogonal matrix. ; Step 2, each element of the phased array transmitting antenna is encoded according to the coding matrix. According to modulation rate Switch codebook to switch radio frequency signals Perform array-coded modulation into a radiated signal radiated signal After being transmitted through space to the target surface, the signal is backscattered by the target surface and received by the single-channel receiving antenna, resulting in a single-channel echo signal. ; Step 3, based on radiation signal Construct an imaging matching mask matrix ; Step 4, based on the imaging matching mask matrix From the echo signal Recovering the back reflection coefficient of the target scene This completes the forward-looking imaging.

[0027] Step 1 specifically involves: Constructing complex orthogonal matrices ,satisfy ,in, Represents the field of complex numbers. Indicates the number of array elements. This indicates the conjugate transpose. Represents the identity matrix; in this embodiment, the complex orthogonal matrix The Hadamard matrix is ​​used.

[0028] definition For complex orthogonal matrices The set of elements that appear in, and ,in, The number of quantization bits for phase modulation of array elements; Introducing one-to-one mapping ; Define the encoding matrix Encoding matrix The elements are .

[0029] Step 2 specifically involves: With the center of the phased array surface as the origin O, a Cartesian coordinate system is constructed. The X and Y axes of the Cartesian coordinate system are parallel to the array surface plane, and the Z axis is perpendicular to the array surface plane and points to the normal direction of the array. The array surface is the geometric plane that defines the phased array for receiving or transmitting signals; The radiation signal For a moment Downward target angle Radiated signal, azimuth Defined as the angle relative to the X-axis, elevation angle Defined as the angle relative to the Z-axis; in, express The composite complex gain of the radiated signals of each sub-encoded element in space is expressed as: in, Indicates the first Far-field radiation pattern of each array element Indicates the first The spatial orientation vector of each array element is represented as: in, This indicates the element spacing of the phased array transmitting antenna along the X-axis. This represents the element spacing of the phased array transmitting antenna along the Y-axis. Indicates the first The element number of each array element in the X-axis direction, Indicates the first The array elements are numbered in the Y-axis direction, and the array element numbers start from 1; Indicates the first The array element in the first The phase modulation coefficients of the secondary encoding, where... The number of quantization bits for phase modulation of array elements; Represents a rectangular window function, symbol period This indicates the time taken for one encoding operation. Total encoding time, radio frequency signal For a total coding time Within a certain time period, the radio frequency signal fed into the phased array transmitting antenna ; when It has the shortest total coding time and the radiated signal Acting on distance After setting the goals, from the perspective of each goal... The reflected signals are synthesized into an echo signal within a single channel. : in, At the speed of light, The target quantity.

[0030] From the encoding matrix The generated array element phase modulation coefficients satisfy orthogonality constraints between different encoding times, thereby enabling single-channel echo... In matching the imaging mask matrix After processing, the observation information can be decoupled, effectively obtaining independent spatial observation degrees of freedom consistent with the number of array elements, that is, satisfying... To ensure that the effective aperture of the array is not reduced and the resolution is not affected, the number of encoding times... It should be at least no less than the number of array elements. ,Right now Therefore, this invention adopts As the encoding length.

[0031] Step 3 specifically involves: Constructing the spacetime radiation field matrix The space is discretized into a grid, where... Represents the field of complex numbers. For all spatial angles to be imaged quantity, For time Number of internal sampling points It is expressed as follows: Constructing an imaging matching mask matrix , ,in, This indicates finding the conjugate of the elements. The Fourier transform basis matrix has the following elements: .

[0032] Step 4 specifically involves: The echo from the single-channel receiving antenna is obtained by using an ADC sampling method. , For time Number of internal sampling points; Construct the back reflection coefficient of the target scene : in, Represents the field of complex numbers. For all spatial angles to be imaged quantity, For time Number of internal sampling points The basis matrix for the inverse Fourier transform is... This represents the Hadamard product of the array.

[0033] This method is applicable to any single-channel multi-element array system, including but not limited to traditional phased arrays, digital arrays, and metamaterial arrays.

[0034] A forward-looking imaging device suitable for a single-channel array, comprising: Memory: Used to store computer programs that implement forward-looking imaging methods suitable for single-channel arrays; Processor: Used to implement a forward-looking imaging method suitable for a single-channel array when executing the computer program.

[0035] A computer-readable storage medium storing a computer program that, when executed by a processor, implements the steps of a forward-looking imaging method suitable for a single-channel array.

[0036] A computer program product includes a computer program that, when executed by a processor, implements a forward-looking imaging method suitable for a single-channel array.

[0037] Experimental Analysis like Figure 3 As shown, the simulation uses a 16x16 square array with an element spacing of half a wavelength. "X", "D", and "U" shapes, composed of point target arrays, are arranged sequentially at 7m, 8m, and 9m intervals in the scene. The simulation parameters are shown in the table below.

[0038] like Figure 4 As shown, the method described in this invention uses only single-channel, single-pulse echo data to perform high-resolution imaging of a three-dimensional scene. Under the same scene, no existing technology has yet been able to achieve high-resolution three-dimensional scene imaging.

Claims

1. A forward-looking imaging system suitable for a single-channel array, characterized in that, The forward-looking imaging system includes A phased array transmitting antenna, a single-channel receiving antenna, and a processor for each array element; The phased array transmit antenna is used to receive radio frequency signals fed from the radio frequency baseband. and according to the encoding matrix According to modulation rate Switch codebook to switch radio frequency signals Perform array-coded modulation into a radiated signal radiated signal It arrives at the target surface after being transported through space; A single-channel receiving antenna is used to receive the echo signal backscattered from the target surface. ; The processor is used to construct the encoding matrix of the phased array transmit antenna. and the radiated signal modulated by the phased array transmitting antenna. Construct an imaging matching mask matrix Based on imaging matching mask matrix The echo signal received from the single-channel receiving antenna Recovering the back reflection coefficient of the target scene This completes the forward-looking imaging.

2. A forward-looking imaging method suitable for single-channel arrays, characterized in that, Based on the system as described in claim 1, the system includes the following steps: Step 1: Construct the encoding matrix of the phased array transmit antenna based on the orthogonal matrix. ; Step 2, each element of the phased array transmit antenna is encoded according to the coding matrix. According to modulation rate Switch codebook to switch radio frequency signals Perform array-coded modulation into a radiated signal radiated signal After being transmitted through space to the target surface, the signal is backscattered by the target surface and received by the single-channel receiving antenna, resulting in a single-channel echo signal. ; Step 3, based on radiation signal Construct an imaging matching mask matrix ; Step 4, based on the imaging matching mask matrix From the echo signal Recovering the back reflection coefficient of the target scene This completes the forward-looking imaging.

3. The method according to claim 2, characterized in that, Step 1 specifically involves: Constructing complex orthogonal matrices ,satisfy ,in, Represents the field of complex numbers. Indicates the number of array elements. This indicates the conjugate transpose. Represents the identity matrix; definition For complex orthogonal matrices The set of elements that appear in, and ,in, The number of quantization bits for phase modulation of array elements; Introducing one-to-one mapping ; Define the encoding matrix Encoding matrix The elements are .

4. The method according to claim 2, characterized in that, Step 2 specifically involves: With the center of the phased array surface as the origin O, a Cartesian coordinate system is constructed. The X and Y axes of the Cartesian coordinate system are parallel to the array surface plane, and the Z axis is perpendicular to the array surface plane and points to the normal direction of the array. The array surface is the geometric plane that defines the phased array for receiving or transmitting signals; The radiation signal For a moment Downward target angle Radiated signal, azimuth Defined as the angle relative to the X-axis, elevation angle Defined as the angle relative to the Z-axis; in, express The composite complex gain of the radiated signals of each sub-encoded element in space is expressed as: in, Indicates the number of array elements. Indicates the first Far-field radiation pattern of each array element Indicates the first The spatial orientation vector of each array element is represented as: in, This indicates the element spacing of the phased array transmitting antenna along the X-axis. This represents the element spacing of the phased array transmitting antenna along the Y-axis. Indicates the first The element number of each array element in the X-axis direction, Indicates the first The array elements are numbered in the Y-axis direction, and the array element numbers start from 1; Indicates the first The array element in the first The phase modulation coefficients of the secondary encoding, where... The number of quantization bits for phase modulation of array elements; Represents a rectangular window function, symbol period This indicates the time taken for one encoding operation. Total encoding time, radio frequency signal For a total coding time Within a certain time period, the radio frequency signal fed into the phased array transmitting antenna ; Radiated signals Acting on distance After setting the goals, from the perspective of each goal... The reflected signals are synthesized into an echo signal within a single channel. : in, At the speed of light, The target quantity.

5. The method according to claim 2, characterized in that, Step 3 specifically involves: Constructing the spacetime radiation field matrix The space is discretized into a grid, where... Represents the field of complex numbers. For all spatial angles to be imaged quantity, For time Number of internal sampling points It is expressed as follows: Constructing an imaging matching mask matrix , ,in, This indicates finding the conjugate of the elements. The Fourier transform basis matrix has the following elements: .

6. The method according to claim 2, characterized in that, Step 4 specifically involves: The echo from the single-channel receiving antenna is obtained by using an ADC sampling method. , For time Number of internal sampling points; Construct the back reflection coefficient of the target scene : in, Represents the field of complex numbers. For all spatial angles to be imaged quantity, For time Number of internal sampling points The basis matrix for the inverse Fourier transform is... This represents the Hadamard product of the array.

7. A forward-looking imaging device suitable for a single-channel array, characterized in that, include: Memory: for storing a computer program that implements the forward-looking imaging method for a single-channel array as described in any one of claims 2 to 6; Processor: for implementing the forward-looking imaging method for a single-channel array as described in any one of claims 2 to 6 when executing the computer program.

8. A computer-readable storage medium, characterized in that, The computer-readable storage medium stores a computer program that, when executed by a processor, implements the steps of the forward-looking imaging method for a single-channel array as described in any one of claims 2 to 6.

9. A computer program product, comprising a computer program, characterized in that, When the computer program is executed by the processor, it implements the forward-looking imaging method for a single-channel array as described in any one of claims 2 to 6.

Images